Field of Invention
The disclosure relates to a manufacturing method and structure of a carbon fiber rim, especially relates to a rim frame's embryo having many through holes and covered by a carbon fiber cloth, whereby a rim having a light weight and a strong structure is obtained.
Description of Related Art
In addition to as a basic means of transportation, bicycles also has composite functions of recreation and sports. After the elevation of research and development ability and the progress of technology, the appearance, ride comfort, body strength, weight, and speed of bicycle all become development focus. Especially for professional athletics racing bike, ride comfort, body strength, weight, and speed are absolutely the goals of the riders.
In order to develop the bicycle toward the direction of lightweight construction, wheels made of carbon fibers have replaced the traditional metal wheels to effectively reduce the total weight of bicycles.
Traditional molding technology of carbon fiber wheels is setting up an annular pocket and filling air into the annular pocket to inflate the annular pocket first, and then multi layers of carbon fiber cloth sequentially cover the annular pocket, wherein the number of the layers of the carbon fiber cloth is determined by the structural strength. Usually, the surface set up by spokes need higher structure strength, and thus 7 layers of carbon fiber cloth need to be covered thereon. The needed structure strength of the other parts of the wheels is lower, and thus 5 layers of carbon fiber cloth need to be covered thereon. However, since manufacturing the traditional carbon fiber wheels needs sequentially covering multi layers of carbon fiber cloth, the manufacturing construction is quite time-consuming and labor-consuming. In addition, it also has to be noticed that whether air is remained between the layers of the carbon fiber cloth. If air is remained, the layers of the carbon fiber cloth cannot be completely and smoothly laminated, and defective with local protruding is thus produced. Therefore, the traditional manufacturing method cannot effectively decrease the defect rate of the carbon fiber wheels. Moreover, the price of the carbon fiber cloth is expensive, and the cost of laminating multi layers of carbon fiber cloth is thus increased. The reasons above all make the price of the carbon fiber cloth wheels not close to the people.
Patent TW 1308527 B discloses “[a] manufacturing method of bicycle rim.” The method laminates multi layers of carbon fiber prepregs to form a primary embryo of a rim. The primary embryo of the rim is placed in a mold to be inflated according to a 3-stage procedure. The outer surfaces of the primary embryo of the rim are forced to be tightly fitted into the inner surface of the mold. At the same time, the primary embryo of the rim is heated to form a secondary embryo of the rim. Finally, the secondary embryo of the rim is set by heating, and the surface of the secondary embryo of the rim is processed to obtain a carbon fiber rim of a bicycle. This method still has the disadvantages of the traditional manufacturing method of carbon fiber wheels. That is, 5-7 layers of carbon fiber prepregs are needed, and thus the manufacturing is time-consuming, high cost, and the defect rate cannot be decreased, as well as it has to be noticed that whether bubbles are generated between adjacent layers when laminating.
Moreover, although the rim made of carbon fiber cloth has the excellent effect of light weight, the carbon fiber wheel cannot meet the requirement of the structure strength and thus deformed easily.
Therefore, some bicycle practitioners further develop bicycle wheel's structure, such as “manufacturing method and structure of bicycle rim” disclosed in TW 200950990A. The manufacturing method includes:
A. forming, wherein a metal material is formed into a tubular body;
B. jointing, wherein two terminals of the tubular body are jointed;
C. rounding, wherein the jointed tubular body is molded to a rim;
D. drilling, wherein the rim is drilled to form several spoke coupling holes;
E. drilling weight decreasing holes, wherein the rim is drilled to form several weight decreasing holes;
F. surface treatment, wherein the edges of the rim are trimmed and the surface of the rim is polished;
G. covering carbon fibers, wherein the surface of the weight decreasing holes and the rim is covered with carbon fibers to seal the weight decreasing hole, and a rim structure is formed.
However, in TW 200950990A, only the weight decreasing holes of the rim are filled with carbon fibers and only the edges of the carbon fibers are joined with the edges of the weight decreasing holes. Therefore, the effect of increasing the structure strength is not obvious.